Yashinoff: WHY? Because I have lots of lenses and I just sold a Takumar 1.4/50 for USD 40 because the guy wanted to use it on his digital. There is, perhaps, new value to these old lenses since the 'official' digital lenses cost a fortune. - David Lyga

There is! Many M42 lenses are going for twice what they were only a year or two ago. Many of the Contax/Yashica mount manual focus SLR lenses are WAY up vs. 2-3 years ago for this exact reason especially the wides as Canon DSLR shooters like them better vs some of the Canon offerings. Glad I loaded myself up for my RTSII and RX a few years ago before the prices mostly rose. Seems to be a new resurgance lately I think a lot because of the Sony NEX cameras and the cheap adapters from China.